Fluid transmission



Sept. 16, 1941. e. A. NAHLMARK 2,255,993

FLUID TRANSMISSION Filed Sept. 9, 1938 4 Shegts-Sheet 1 efizveizzar' zz/z/zar Q @afi/mri p 1941. G. A; WAHLMARK ,2

FLUID TRANSMISSION Filed Sept. 9. 1938 4 Sheets-Sheet 2 167 1%. 5 :5; ZZZ/672 ar Zwzizgf a Wei/1720f p 1941- G. A. WAHLMARK 2,255,993

FLUID TRANSMISSION Filed Sept. 9, 1938 4 Shets-Sheet 3 19/ I fiv e izfor 'zzizizar a Wail man? 1941- G. A. WAHLMARK 2,255,993

FLUID TRANSMISSION Filed Sept. 9. 1938 4 Sheets-Sheet 4 0%20605070 fizz/war a Wei/2260i Patented Sept. 16, 1941 UNITED STATES PATENT OFFICE FLUID TRANSMISSION Gunnar A. Walilmark, Rockford, Ill. Application September 9, 1938, Serial No. 229,223

9 Claims. (Cl. 60-53) More particularly, the invention relates to a fluid transmission for operating a driven shaft at a speed diflerent from that of a drive shaft, it being the general object of the invention to provide a new and improved mechanism of this type.

Another object is to provide a new and improved fluid transmission having a fluid pump adapted to be driven by a prime mover and a fluid motor together with a circuit connecting the pump and motor, including a pumping device for supplying fluid under pressure to the intake of the pump and the outlet of the motor.

Another object is to provide a new and improved fluid transmission embodying a fluid pump, a fluid motor, a circuit connecting the pump outlet to the motor inlet, and the motor outlet to the pump inlet, and valve mechanism for controlling the flow oi fluid in the circuit and operable to start and stop the motor and to change its direction of rotation.

Another'object is to provide a fluid transmission having a fluid motor with means for braking the motor operable to restrict the fluid flowing from the outlet of the motor while maintaining the supply of fluid to the inlet of the motor.

Another object is to provide a new and improved fluid transmission having a multiple piston variable displacement pump and a multiple piston variable displacement motor, together with control means for simultaneously increas ing-the stroke of the pump and decreasing the stroke or the motor, and vice versa.

Other objects will become readily apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a fragmentary elevation partly in vertical section through the drive and driven shafts of a transmission showing a preferred form of the invention.

Fig. la is a fragmentary section along the lines -141 of Fig. 1.

Fig. 1b is a fragmentary section along the lines 1b-1b of Fig. 1.

Fig. 2 is a section along the line 2--2 of Fig. l.

Fig. 3 is a transverse section approximately along the line 3-3 of Fig. 1 showing the control valve in its neutral position.

Fig. 4 is a similar view showing the control valve in the position for eilecting clockwise rotation of the motor, as viewed from the left hand end of Fig. 1.

Fig. 5 is a similar view showing the valve in the position to stop and brake the motor aiter operation in a clockwise direction.

Fig. 8 is a fragmentary plan view of the unitary control for the pump and motor approximately along the line 2-4 of Fig. 1.

Fig. 7 is a view approximately along the line 1-1 oi. Fig. l.

Fig. 8 is a fragmentary section along the line H of Fig. 7.

Fig. 9 is a diagrammatic representation of the circuit.

While the invention is susceptible of embodiment in many diflerent forms, there is shown in the drawings and hereinafter described in detail one such embodiment, with the understanding that the present disclosure is to be considered as an exempliflcation or the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

In the formshown in the drawings, the invention comprises a casing l0 having suitable supporting brackets l I formed integrally therewith. The lower portion of the casing forms a fluid reservoir l2, whereas the upper portion of the casing contains a multiple piston fluid pump designated generally I! and a multiple piston fluid motor designated generally I. An annular adapter I! is secured to the left hand end of the casing by means of a plurality of bolts l6 and has a flange l1 projecting into an opening 18 in the end wall of the casing. This adapter is arranged to support a prime mover l9 herein shown in the form of an electric motor.

The pump it has a shaft 20 axially aligned and connected to the prime mover shaft by means of a coupling device 2|. The fluid motor ll has a shaft 22 projecting out through the right hand end of the casing so as to be avail able for connection to the mechanism to be driven. As illustrated herein, the shafts of the prime mover, the pump I3, and the motor it are in axial alignment.

The pump I3 is or the multiple piston wobbier type and comprises a casing 25 supported at one end in a bore 26 of the adapter flange II. A cylinder block 21 has a plurality of annularly disposed cylinders 28 in which pistons 29 are reciprocably mounted. The cylinder block has a flange 30 abutting the right hand end of the casing 25. A plate 3| is positioned'against the end of the cylinder block and is provided with a plurality of recesses 32 aligned with the cylinders 28 so as to form the head ends thereof.

so ripheral wall of a valve chamber ll wallofwhichisformed theotherbytheadjacentendofa by a roller bearing ll.

* (see Fig. is) for the NW of centrically from the right hand end of ate outlet passage 4! connected to outlet arcu gports 46, the outlets 4! being 3 outwardly of the cylinder ports 42, and the inlet fports beingdisposedradiallyinwardlyofthe cylinder ports. Thevalve ll has a peripheral i i flange 41 which. during the eccentric movement of the valve member,.alternately connects i the cylinder ports 42 with the inlet ports II and ithe outlet ports 4! in the manner more fully described in said prior application.

I The pistons 29 of the pump it are arranged to be actuated by means of a wobbler device which 3 comprises an annular'member II which is pivotall mounted on the shaft by meansof a pin il. Aball bearinghas one race 82 securedto the I member so that the other race It engages the 1 adjacent ends of the piston 2!. The angular position of the wobbler on the shaft may be adjusted by means of a key-like member 54 which has a beveled end It which engages a roller I1 mounted on the wobbler member II. The member 54 may be adjusted longitudinally of the ishaf t by means including a lever w which is pivoted intermediate its ends at It on the cylinder block and has its lower end eng88i 8 Ina hole 59 in a collar 8| which loosely surrounds the shaft 2.. The collar ll forms the outer race of a ball hearing I, the inner race 82 of which is secured between laterally spaced upstanding lugs ii on the member 54. It will be readily apparent that by pivoting the lever 50' about its fulcrum ii, the collar it will be moved longitudinally of the shaft and that this movement gof the collar will effect a similar movement of the member 54 and causethebeveled end it thereof to swing the wobbler member II in a counter- Zclockwise direction or permit it to swing in. a iclockwise direction depending upon the direction of movement of the member ll,

5 The fluid motor I4 is somewhat similarin construction to the fluid pump it. Thus, the fluid motor has a casing 06 provided with an outwardly extending flange .1 at its right hand end, this ilange being attached to the transmission casing ill by means of a plurality of screw devices II.

An annular cylinder block I is positioned in the.

slides in a longitudinal groove II in the shaft and end positioned against the adjacent end of the casing II. A plate I! is positioned against the adjacent end of the cylinder block and has a plurality of recesses ll aligned with the cylinders ll so as to form head ends therefor. The plate 13 also has a plurality of cylinder ports 14', one for each cylinder. The plate is secured to the cylinder block by means of a plurality of screw devices 15. An annular member or ring 16 is positioned against the plate 13 and between the plate and the adjacent face ll of the valve housing 30 so as to define a chamber it for a wheellike valve member 19.

.The shaft 22 of the motor I is rotatably supported at one end by means of a pair of ball bearings 8|, the outer races of which are fitted in a bore 8] in the right hand end of the casing 36., The inner races of the ball bearings are secured against each other and against a shoulder '2 on the shaft 22 by means of a nut 83. The other end of the shaft is mounted in a roller bearing 84, the outer race of which is supported partly in the cylinder block and partly in the plate 13. The shaft is provided with an eccentric pin (Fig. 1b) which drives the valve I! through an intermediate ball bearing 86.

Here again the valve I9 and its associated ports function in a manner similar to that shown in the hereinbefore mentioned prior application The adjacent portion of the valve housing 38 has an arcuate passage connecting with a plurality of ports 9| which communicate with the chamber 18 radially outwardly of the cylinder ports 14. The housing 36 also has an arcute port '2 communicating with a plurality of ports 83 which connect with the chamber I8 radially inwardly of the cylinder ports H. For a clockwise rotation of the motor shaft, the passage 92 and ports 93 form the inlet to the motor and the passage 90 and the ports 9i form the outlet. For a counterclockwise rotation of the .motor shaft, this is reversed. I

The motor is provided with an adjustable wobbler comprising an annular member 95 which is pivoted on the shaft 22 by means of a pin 95. A ball hearing has one race 91 secured to the a member 95 and has its other race 98 positioned to engage the adjacent ends of the pistons II. The means for adjusting the wobbler angularly on the shaft comprises a bar I00 reciprocably mounted in a longitudinal slot II in the shaft 22 and provided with rack teeth I02 which mesh with a pinion I03 formed on .a. short shaft I (Figs. 1 and 7) rotatably mounted in a transverse v bore III in the shaft 22. The outer ends of the shaft I are formed with pinions I09 and m which mesh with internal gear segments Ill and H2 secured'to the member iiiv by means of screw 7 devices 3 and Ill. By reciprocatingthe rack bar I", the shaft I rotates with the result that 1 the pinions II! and Ill] actuate the wobbler 1 member 85 through the segmental gears Ill and H2. Th means for reciprocating the rack bar is similar to that provided for reciprocating the member 54 in the pump. As shown in'Flg. 1,

this means comprises a lever H5 fulcrumed intermediate its ends at 6 in the cylinder block I! and is provided with a plurality of anoutwardly extending flange 12 at its left hand 75 In its preferred form, the invention contourand positioned with its lower end in a bore I I1 formed in a collar lit loosely surrounding the shaft 22. A portion ll! of this collar forms the outer race of a ball bearing, the inner race l2. of which is fitted intermediate upstanding lugs l2l on the rack bar IIIIL.

plates the provision of a unitary control means for simultaneously adjusting the strokes of the pump I6 and the motor I6. As shown in the drawings, an'dmoreparticularlyinrigs. 1and6,

, 2,132,813, dated October 11, 1938. A cup-shaped the upper end of the motor stroke adjusting 5 lever III extends into an opening lfl formed in a cylindrical rod I26 which is slldably mounted in a bracket I21 which is secured to the upper 1 surface of the casing 66 by means of screw devices I26. A pin I26 connects the upper end of the lever to the member I26 and serves as a support for the lever. The upper end of the pump stroke adjusting lever 66' is'similarly connected by means of a pin I66 to a cylindrical bar I6I which is reciprocably mounted in a bracket I62 secured to the upper surface of the pump casing 26 by means of screw devices I66. A portion of the bar I6 Lis formed with teeth I64 which mesh with pinion teeth I36 formed on a shaft I66.

The shaft I66 extends transversely of the rack bar I6I and is rotatably mounted in the bracket I62. One end of the shaft I66 projects beyond the bracket I62, as shown in Fig. 6, so that a reduced portion I61 thereof may be coupled to an operating shaft I66 by means of a coupling collar I66 which is secured-to the shaft I61 by a pin I46 and is secured to the shaft I66 by means of a key I. The shaft I66 extends out through the forward wall I42 of the casing I6 and has a projecting end I66 arranged for the reception of a suitable hand wheel I46.

Upon rotation of the shaft I66, the lever 66' will be pivoted about its fulcrum through the intervening rack and pinion connection I64, I66.

A connection is provided intermediate the shaft I66 and the member I26 so that the stroke of the motor I4 will be decreased as the stroke of the pump I6 is increased, and vice versa, thus providing for a continuous shift from stand-still to maximum speed of the driven shaft 22. shown herein, this connection is in the form of a link comprising a rod I46, bifurcated at one end and secured to the member I26 by means of a pin I46. The other end of the rod I66 is threaded at I41 and extends through a bore in an oflset 45 connecting member I46, nuts I46 cooperating with the threaded portion of the rod to secure member I46 adjustably to the rod. The other end of the member I46 is secured to one end of the shaft I66 by means of an eccentric I66 which 50 is suitably secured to the shaft I66 or formed integrally therewith and passes through a bore I6I in the member I46. The parts are held together by means of a washer I62 and a set screw I66.

In the present form of the invention, a relatively small constant volume rotary pump desig nated generally I65 is driven by means of a shaft I66 from the pump shaft 26. As shown most clearly in Fig. in, an eccentric pin I61 on the pump shaft engages in an eccentric recess in a flange I66 on the adjacent end of the shaft I66 to form a driving connection therebetween. The shaft I66 is journaled eccentrically in a bushing I66 positioned in a bore I66 in the housing 66.

The pump I66 consists of an internally toothed member I6I which is rotatably mounted in the bore I66 adjacent one end of the bushing I66, an externally toothed pinion I62 secured to the shaft I66 by means of a key I66 and a crescent guard 70 member I64 which issecured to the bushing I66 by means of pins I66. This rotary pump may be of the gear type or, preferably, of the type disclosed in my prior application Serial No. 675,218, filed June 10, 1933 now issued as Patent No.

member I66 is inserted in the fleht'hand endof thebore I66 (Fig. 1) soastoholdthepartsin assembled relationship and is secured to the housing 66 by means of screw devices I61.

Itis contemplated that the pump I6 and motor I6 will be incorporated in a fluid circuit with a valve device such as IlliFigs. 1, 3, 4, 5 and 6) and with the mechanisms as hereinafter set forth, in order to faciliate the starting, stopping, braking and reversing of the motor I4. Portions of this circuit are formed in or attached to the housing 66, which housing in turn is bolted to the pump parts and easing by means of a plurality of boltsslli, and is bolted to the motor parts and casing-by means of a plurality of bolts I12 so as to form a structural connection therebetween. I

The valve I16, asshown most clearly in Figs. 3, 4 and 5, is of the'cylindrical, reciprocatory type and has four operative positions as determined by the engagement of a detent device I16 with annular grooves I16, I11, I16, and I16 formed in one end of the valve. The valve also has a neutral position, as shown in Fig. 3 wherein the detent devise is positioned intermediate the grooves I11 and I16. The cylindrical valve, reciprocable in a bore I66 formed in the housing 66, is operable bymeans of a stern I6I threaded into and pinned to one end thereof, as shown in F18. 4. The valve has an axial port I62 which communicates at one end with an annular recess I66. by means of a diametrical port I64 and communicates at its other end with an annular recess I66 by means of a diametrlcal port I66. Intermediate its ends, the port I62 connects with the adjacent periphery of the valve by means of opposed recesses I61. The valve also has a pair of annular recesses I66 and I66 formed therein which operate in a manner hereinafter more fully set forth.

The housing 66 has a number of ports and passages formed or cored therein which cooeprate with the valve in variously directing the fluid from the pump to the motor. Thus, as illustrated in Figs. 1, 3. 4, 5 and 9, an annular fluid supply passage I66 communicates with the midportion of the bore I66 and is also connected to the pump outlet passage 66. An annular passage I6I to the right of the passage I66 (Fig. 3) communicates with the motor passage 62 by means of a recess I62 (Fig. 1) and therethrough with the ports 66 tosupply fluid to the motor during clockwise rotation thereof when looking at the right hand end of Fig. 1. Fig. 4 shows the valve in the position 5 for effecting such clockwise rotation of the motor.

An annular passage I66 positioned to the left of the passage I66 (Fig. 3) is connected by means of a recess I64 (Fig. l) with the motor passage 66 and through said passage withthe motor ports 6| for receiving the fluid discharged by the motor when rotating in a clockwise direction and with the valve located as shown in Fig. 4.

The housing 66 is also formed with an annular recess I66 as shown at the right hand end of Figs. 3, 4 and 5 and an annular recess I66 as shown at the left hand of said figures, together with a passage I61 extending upwardly from the recess I66, a passage I66 extending upwardly from the recess I 66 and a suitable interconnecting passage I66 between the upper ends of the passages I61 and I66. These last mentioned recesses and passages are for receiving fluid from the discharge side of the motor and also from an outlet port 266 of the rotary pump I66.

The means for braking the motor consists es- 4 sentially of means for preventing-or New 1 thedischargeoi'iiuidbythemotor while at the sametimemaintainingtheinletportstothe motor and the cylinders fllledwith fluid. illustrated herein. the housing ll is provided with annular recesses Ill and III communicating with the bore Ill adjacent the recesses Ill and Ill,

' respectively. Ports Ill and Ill connect these.

recesses respectively with the passages Ill and Ill. 'lhese ports are normally closed by means of vcheck valves Ill and Ill which are pressed into engagement with annular seats Ill and Ill (not shown) toports Ill and in (i ls. ii formedrespectlveiyintheupperportionsoithe cylinder blocks II and ll. I'romthese ports, the

.nuidissprayed cats the wobbler devices and adjacent bearings by means of coiled springs Ill and Ill, the tension of which is adjustable, by means of screw devices Ill and III.

' In a manner more fully described hereinafter,

the pump lll is connected to lllpply'fluid under pressures of one hundred to one hundred flity pounds per square inch to the. return portion of the circuit from the outlet of the'motor ll to the inlet of the-pump II. This pressure ispreferably maintained by means of a pressure operated bypass valve designated generally Ill (Fig. 3);

This valve comprises a supporting member Ill which is secured to a dependinl p rtion II! of the housing ll by means ofa pipe connection Ill which communicates at its upper end with a chamber Ill in the housing ll and at its lower endwith a port IIl in the valve casing Ill. The port IIl communicates with an annular chamber III, from which fluid is arranged to flow out through acentral discharge port III, the

and mechanism. This treatment of the fluid also resultsin cooling of the fluid as well aslubri tionofthemechanism.

Fig. 9- illustrates. tically, and ma simplifled manner, the principal parts and the fluid circuit of the preferred form of the inven-' tion. The valve III is shown in its neutral position, thesame as in Fig. 3. The pump Ill is shown with an inlet port Ill and an outlet port. 1 Ill" which communicates with the outlet passage Ill. The high presure relief valve Ill is illustrated controlling'a passage III which ex-l right hand end of l 'ig;-=..i. 'rhe shaft II of the,

motor Il may be connected to a device to. be driven at variable speeds. "The reservoir II and the fluid circuit are iilled with a suitable operating fluid such as oil. with the, parts in the po-' sition illustrated in Figs. 1 to 3 andl to 9, the

intervening portion of the casing forming an an-' nular valve seat IIl against which a flat disklike valve IIl is urged by acoiled spring IIl. Preferably, the disk valve IIl is mounted on a diaphragm I which is clamped between one face of the valve casing Ill and the adjacent face of a cup-shaped closure III which houses the spring III and forms a support for a spring adjusting screw device IIl.. Fluid passing out through the port III is permitted to flow into the reservoir II in the lower portion of the casing ll.

In order to relieve the pressure in the high pressure supply passage Ill in the event the motorv is accidentally stalled, a high pressure relief valve Ill is preferably included in the mancounter-clockwise direction so a to increase the stroke of the pump; fluid is discharged by the pump ll is set at substantially zem s'troke, and the motor ll is set at approximately "maximum stroke. The valve in is in its neutral position. Upon turning the hand wheel ill. (Fig. 6) in a pump into the supply passage lll.', S l the her illustrated in Fig. 3. This valve is normally seated against an'annular seat Ill surrounding the discharge end of a high pressure relief port IlI, the other endgof which is connected to the e Ill by means of a recess Ill. A coiled spring Ill is positionedjlntermediatethe valve Ill and a plug Ill screw-threaded in the housing ll so as to maintain the valve Ill seated under normal working conditions. Fluid is supplied to the inlet of the rotary pump Ill by means including a conduit Ill (Fig. l) which connects at its upper end to an inlet port Ill of the pump and connects at its lower end to a port IlI formed in the left hand end wall of the casing ll. The

port IlI in turn communicates with a strainer chamber Ill formed in a detachable plate Ill,

the fluid in the reservoir II being arranged to flow into the chamber Ill through'a suitable strainer Ill. The strainer is mounted on the plate Ill (which is preferably detachable from the casing ll) so that it may be removed for cleaning and renewal-purposes.

In order to cool the fluid, the-casing II is pref-- erably provided with an air channel Ill which extends through the body of-the fluid, the normal level of which is indicated at Ill. Ii'urtherinore, the fluid discharged from the port III is preferright hand end of Fig. 1.

ably conducted by means oi suitable conduits valve is in the neutral position shown in Fig. 3, this fluid passes through the openings Ill and the axial port "I of .the valve and thence through the ports Ill and Ill and into the re-.

cesses Ill and Ill (Fig. 3). Bince'the pump Ill is in operation and is also supplying fluid through the port Ill and the intermediate passage Ill and ill to the recesses Ill and ill, the excess fluid pas es out through, the pipe connection Ill and past the valve IIl. The fluid discharged is conducted to the lubricstingports Ill and Ill and is dlscharged'through the nozzles Illand Ill onto the Wobbler mechanisms. Under these conditions, the inlet and-outlet ports of the motor gll are subjected to the same pressure with result that the motor does not operate.

Upon shifting the valye Ill to the position illustrated'in Fig. 4, fluidfrom the supply passage Ill passes into theanriular e Ill and'on-' to the" motor passage, lI andmotor ports ll.

when. the ports ll-are used as supply orlnlet ports for the motor, the motor shaft II will operate in a clockwise direction a viewed from the I The speed of the motor will depend upon the position of the hand wheel I ll, 'theconnections intermediate the motor stroke adjusting bar Ill and the pump stroke adiusting member ll. being such as to cause the strokeoi the motor tobe shortened as the stroke of the pump is increased. Thus, as the volume of the fluid discharged by the pump increases from zero to a maximum, the volumetric capacity of the motor decreases from a maximum to a minimum to provide an extremely wide range of of the shaft 22. with the,valve ill in the position shown in Fig. 4. the fluid discharged through nozzle-like ports as f and Illonto-the wobhler devices so as to lubriv thebythemotorllpassesoutthroughtheportsll (Fig. 1) and passage ll andthrough theintermediate recess I94 to the annular passage |!l.

From this e, the fluid passes through the opposed recesses I" of the valve and into the axial port lflthereof, the fluid then discharging through the diametrical port I" into the return recess I. With the valve in the position shown mm. 4, the speedof themotorshaft llmaybe varied by operating the hand wheel I.

In order to stop the motor and apply a brakin effect thereto, the valve I'll is moved to the position shown in Fig. 5. When in this position, the fluid discharged by the motor into the annue I83 is shut off from direct communication with the axial bore is! of the valve because the opposed recesses Ill of the valve have been moved out of communication with the passage I". Fluid from the passage I" can only escape through the port 204 and in order to do so must open the valve 2" against the action of the spring Ill. The spring is selected of the proper strength to create the desired braking action. In order to maintain the cylinders of the motor fllled with fluid during the braking period, the annular supply passage Ill remains in communication with the fluid supp y and return circuits as shown in the right hand portion of Fig. 5.

When it is desired to operate the motor in a reverse direction, it is merely necessary to shift the valve illl to 'its extreme right hand position wherein the detent device I15 (Fig. 3) engages the annular groove I19. After operation in the reverse direction, movement of the valve so that the detent device engages in the groove I'll causes a braking action in a manner similar to that already described with respect to Fig. 5. If no braking action is desired, the valve I may be moved directly to the position shown in Fig. 3. Furthermore, if no braking action is desired, the check valves 205 and 206 may be removed. If braking action is desired for only one direction of rotation, the corresponding check valve may be removed.

If for any reason the pressure in the motor supply passage I90 exceeds a safe value, the valve 230 is arranged to open and permit the fluid to return to the reservoir through the pipe 2|! and past the valve 224. It is contemplated that the spring 234 will be selected of such strength that the valve 230 will be closed under all normal operating conditions, but so that the valve will open if, for example, the motor shaft 22 is stalled.

It is believed readily apparent that the'invention in its preferred form provides for a wide range of speeds of the motor shaft and embodies a simple control mechanism for adjusting this speed. With the prime mover operating, the starting, stopping, braking and reversing of the motor are entirely under the control of the valve I'll. By providing means for cooling the fluid, as well as a means for using the bypassed fluid for lubricating the parts of the pump and motor, the transmission is readily adapted for continuous operation over long periods of time.

The provision of'a make-up pump such as the pump I55 for maintaining fluid at a predetermined pressure at the intake of the pump and the outlet of the motor, insures the complete fllling of the pump cylinders on the intake strokes and reduces noise and heating. If the pump cylinders were not completely filled by fluid under pressure, there would be a tendency for fluid to flow from the discharge passage of the pump back into thecylinders which are about to discharge in order to fill the spacecaused by the incomplete filling of the cylinder during the suction stroke of its piston. The elimination of such return flow from the pressure side to theincompletely filled cylinders is effective to reduce the heating and eliminate noise. Furthermore, by Pr viding a pump means for maintaining a pressure on the intake of the main pump, the fluid supplied to the main pump serves as a means for moving the pump pistons through their suction stroke.

In the preferred form of the invention, the

" pump and motor shafts are aligned and the pump casing and motor casing are rigidly secured to-' gether by means including the housing ll. The rotary pump also has its driving shaft aligned with the pump ll, this facilitating the driving of the rotary pump by means of a shaft connected to the adjacent end of the pump shaft 2.. .As

shown in Figs. 1 and 6, theeccentrlc III of the intermediate portion of said shaft and a pump control member connected at one end to said element and extending outwardly intermediate adjacent cylinders of the pump, a motor having a driven shaft, a plurality of parallel piston and cylinder devices arranged annularly about an intermediate portion of said driven shaft, an adjustable wobbler on said shaft operable by the motor pistons, means for adjusting said wobbler comprising a motor control element slidably mounted on said intermediate portion of the driven shaft and a motor control member having one end connected to said element and its other end extending outwardly intermediate adjacent cylinders of the motor, means for controlling the flow of fluid from said pump to said motor, andmeans for simultaneously adjusting the strokes of the pump and motor pistons connected to the outwardly extending endsof said pump and motor control members.

2. A fluid transmission comprising, in combination, a pump having a drive shaft, a' plurality of parallel piston and cylinder devices arranged annularly about an intermediate portion of said shaft, an adjustable device on said shaft for actuating the pump pistons, means for adlusting said device comprising a pump control element movable longitudinally of said intermediate portion of said shaft, a ball bearing having one race secured to said pump control element and a pump control lever connected at one end to the outer race of said bearing and extending outwardly intermediate adjacent cylinders of the pump, a motor having a driven shaft, a plurality of parallel piston and cylinder devices arranged annularly about an intermediate portion of said driven shaft, an adjustable device on said shaft operable by the motor pistons, means for adjusting said last mentioned device comprising a motor control element movable longitudinally of said intermediateportion of the driven shaft, a ball bearing having one race secured to said motorcontrol element and a motor control lever having one end connected to the other race of said bearing and its other end extending outwardly intermediate adjacent cylinders of the motor, means for controlling the flow of fluid from said. pump to said motor, and means for simultaneously adjusting the strokes of. the pump and-motor pistons connected to the outwardly. extending ends of said pump and motor control levers. p s 3. A fluid transmission comprising, in combination, a casing, a fluidreservoir in thelower portion of said casing. a pu p having inlet and outlet ports, a motor having inlet and outlet ports, said pump and motor being positioned in the upper portion of said casing, means forming a supply passage-between the outlet port of, the

pump and the inlet port of the motor, means forming a return passage from the outlet port v -of the motor to the inlet port of the pump, an

auxiliary pump having a discharge port connected to said, return passage to 8119917 fluid under pressure to the inlet of the first mentioned pump,' a fluid operated valve for discharging ex-.

cess fluid from said return passage, and means for directing said excess fluid onto the pump and motor parts to lubricate said parts and cool said fluid prior to its return to said reservoir.

4. A fluid transmission comprising, in combination, a casing, a reservoir located in said casing, a pump having a drive shaft, a plurality ,of piston and cylinder devices, a wobble plate driven by said shaft for actuatingthe pump pistons and means for controllingth'e inlet and outlet of fluid to and from the pump cylinders. a motor having a driven shaft, a plurality of piston and cylinder devices, a wobble plate carried by said motor shaft forconverting the reciprocatory movement of the motor pistons into rotary movement of the motor shaft and means for controlling the inlet and outlet of fluid to and from the motor cylinders, means forming a supply passage connecting the outlet of the pump to the inlet of the motor, means forming a retum passage from the outlet of the motor to the inlet of the pump, means for withdrawing fluid from said reservoir and for discharging said fluid'under' pressure into said return passage, and means for conducting excess fluid from said return passage and discharging said excess fluid onto the wobble plates of the pump and motor cameos pump outlet, to the motor inlet and the motor,

outlet to the pump inlet, valve mechanism in said stationary element interposed in the fluid passages and including a shiftable valve member to control the starting. stopping and reversing of said motor, an auxiliary pump' almlocated in said stationary element and driven from the adiacent end of said pump shaft,a supply passage for said auxiliary pump opening outwardly of said stationary element, and a discharge pe formed ;wholly within a said s tionary member and opening to the e co ecting the motor outlet to the pump inlet intermediate said valve mechanism and the pump inlet to supply'makeup fluid under pressure to the inlet of said pump.

8. A fluid transmission comprising, ncombination, a pump having inlet and outlet ports, a

- motor having inlet and outlet ports, means form-.

ing a discharge passage leading from the outlet port of said pump, a return passage leading. to the inlet port of said pump and passages leading to the inlet and outlet ports respectively of said motor, valve mechanism interposed between the I passages of said pump and the passages of said motor including a valve member having start, stop and brake positions, a by-pass passage in said valve mechanism leading to said return pasleading from the outlet port of said pump, means forming a return passage leading to the inlet port of the pump, means forming passages leading to'the inlet and the outlet ports of said motor alternately serving, as supply or discharge pasl sages depending upon the direction of operation ,of said motor, .va reversing valve mechanism including a valve housing having a longitudinal bore to which said passages open, passages leading from the bore in said housing to the return passage for said pump, a spring pressed valve for each of said last named passages permitting s6 flow only from the bore to said return passage,

to lubricate said parts and to cool the fluid prior to its return to said reservoir. a

5. A fluid transmission comprising, in combination, a pump having a drive shaft, a plurality of piston and cylinder devices, means at one end of the cylinders operable by the drive shaft;for

actuating the pistons, a valve driven from said shaft positioned adjacent the -other end of said cylinders for controlling the inlet and outlet of fluid to and from the cylinders, a motor having a driven shaft, a'plurality of piston and cylinder devices, means carried by said motor shaft for converting the reciprocatory movement of the motor pistons into rotary movement of the motor shaft, and means including a valve driven from one end of the motor shaft for controlling the inlet and outlet of fluid to and from the motor cylinders, a supporting structure for said pump and said motor placing the pump and motor shafts in alinement and with their valve operating ends positioned toward each other including a stationary element intermediate the adjacent ends of the pump and motor, fluid passages and a shiftable valve member having forward and reverse positions and intermediate stop positions,

one for each direction of operation of said pump, said valvemember when in an intermediate stop position connecting the discharge passageof said pump with said return passage for said pump, connecting the then discharge passage for said /motor with-the return passage for said pump through one of said spring valve control passages, and connecting the then supply passage for said motor with said return pump to brake the motor. 1 g 8. A fluid transmission comprising, in combination, a pump having a drive shaft, a plurality of parallel piston and cylinder devices arranged annularly about anintermediate portion of said passage for said shaft, an adjustable Wobbler on said shaft for actuating the pistons of said devices, means for adjusting said Wobbler comprising a pump control element movable longitudinally of and adjacent said intermediate portion of said shaft and v a pump control member connected at one end to said element and extending outwardly intermediate adjacent cylinders of the pump, a motor formed in said stationary element connecting the havinga driven shaft, a plurality of parallel pis- 9. A fluid transmission comprising, in combina- 15 tion, a casing, a fluid reservoir in said casing, a pump in said casing having inlet and outlet ports, a motor in said casing having inlet and outlet ports. means forming a supply passage between the outlet port of the pump and the inlet port of the motor, means forming a return passage from the outlet, port of the motor to the inlet port of the pump, van auxiliary pump having-a discharge port connected to said return passage to supply fluid under-pressure to the inlet of the flrst mentioned pump, and means fordlscharging excess fluid from said auxiliary pump onto the flrst mentioned pump and motor cate said parts. GUNNAR A. WAHIMARK.

parts to lubri- 

